The fastest way to get rid of bad questions is to close them and make sure they have a downvote. Here are some ideas for searching for bad questions...
#1 - Closed questions with no answers and no upvotes
In this previous post, I suggested searching for:
closed:1 migrated:0 answers:0 score:0
(Note that score:0 matches only posts with score=0, whereas score:anything_else matches score>=anything_else)
On 3 August 2013, there were ~1300 results from this search, but apparently multiple people got in on the cleanup and there are now (18 Aug) only 77 results, most of them merged duplicates which will never be deleted (merged questions are another type of "locked," so they'll always fail that test.)
And if you look at the results of:
closed:1 migrated:0 answers:0 score:-1...-1
(If you just use score:-1, you get all the questions with score >= -1. The syntax shown limits it to only -1)
You'll see that once you go 30 days back, there are very, very few -1 questions left. Yay! All sorts of bad questions gone.
#2 - Closed questions with no answers and one upvote
This next one isn't as dramatic, search for closed but upvoted questions:
closed:1 migrated:0 answers:0 score:1
Since score:1 means score>=1 this matches a few questions with multiple upvotes, but most of them are only +1. (As of 19 Aug 2013, this search gives ~370 results, and ~300 of them are at +1.)
The questions that this search turns up that are +1 are a mixed bag - when I go through the list, I see some that are ok, but many others I think are bad. If they get downvoted to 0 and they're a year old, they'll get auto-deleted. If they get downvoted to -1, they'll get deleted once they're a month old.
#3 - Questions (open or closed) with no answers and no upvotes
(This is newly added in Sep 2014... I'm not sure how I missed it when I first posted.)
answers:0 score:0 locked:0
There are tons of these and many of them are crappy. If so, give them a downvote so they're at -1 and they'll get taken care of on the next Saturday cleanup. I usually sort the search results by date and look through the oldest ones first. I find it's easier to spot old crappy questions.
When I added this idea on 9 Sep 2014, this search gave ~8800 results, now on 12 Sep it's down to 8400, so yay!
Today, I thought of a complementary search:
answers:0 score:1 locked:0
Lots of the questions with just 1 vote are also crappy, so if one person votes those down to 0, they'll show up when someone else does the earlier search for votes:0